Photographic emulsions containing cyclic ketone sensitizers



United States Patent Oiiice 3,165,410 Patented Jan. 12, 1965 New Jersey No Drawing. Filed May 29, 1961, Ser. No. 113,065 11 Claims. (Cl. 96-107) This' invention concerns photographic silver halide emulsions, and more particularly, photographic silver halide emulsions containing a novel sensitizing material.

5 It is well known in the photographic art that silver halide emulsions can be chemically sensitized with a variety of materials in order to increase the speed thereof. Certain chemical sensitizers are believed to react with the silver halide to form on the surface of the silver halide minute amounts of silver sulfide, silver, or other noble metals. In addition, other classes of compounds can be utilized to increase the sensitivity of photographic silver halide emulsions that apparently do not enter into chemical combination with the silver halide.

It is an object of this invention to provide photographic silver halide emulsions containing novel sensitizers.

It is another object of this invention to providenew photographic silver halide emulsions having increased sensitivity without accompanying undesirable increases in fog.

It is still another object of this invention to provide photographic silver halide emulsions sensitized with novel cyclic sensitizer compounds.

It is likewise an object of this invention to provide'novel photographic elements having coated thereon silver halide emulsions containing new chemical sensitizers.

These and other objects of the invention are accomplished by incorporating into photographic. silver halide emulsions sensitizing amounts of certain cyclic ketones containing carbonyl radicals.

The ketonic sensitizers of the invention are 3-alkyl-3- hydroxycyclohexanones and 3-alkyl-2-cyclohexenones having at least one carbonyl radical attached to the cyclic nucleus, the 4 and 6 positions on the cyclic nucleus being points of attachment for the carbonyl radicals. Various substituents can also be attached to the 5 position on the cyclic nucleus including alkyl, acyl, alkoxy carbonyl, alkoxy, pyridyl etc. Preferred ketonic sensitizers of the invention have the formulas R' R B R R R -O wherein R and R are alkyl radicals having 1 to 6 carbon atoms and wherein R R R and R are hydrogen atoms or carbonyl radicals having the formulas wherein R and R are alkyl radicals having 1 to 6 carbon atoms. At least one of the substituents in the group R and R or R and R is a carbonyl radical. Typical alkyl radicals include methyl, ethyl, n-propyl, isopropyl, nbutyl, tert.-butyl, n-phenyl, n-hexyl and the like.

The ketonic addenda of the invention can be added to photographic silver halide emulsions for the purpose of increasing the sensitivity or speed thereof.

The preparation of photographic silver halide emulsions such as are suitably sensitized with the addenda ofthe invention typically involves three separate operations: (1) emulsification and digestion of silver halide, (2) the freeing of the emulsion of excess water-soluble salts, suitably by washing with water, and (3) the second digestion or after-ripening to obtain increased emulsion speed or sensitivity. (Mees, The 'Theory of the Photographic Process, 1954.) The sensitizers of our invention can be added to the emulsion before the final digestion or afterripening, or they can be added immediately 'prior to the coating.

The particular quantity of the present ketonic sensitizers used in a given emulsion \can vary, depending upon the effects desired, degree of ripening, silver content of the emulsion, etc. The amount used is also dependent upon the particular stage at which the sensitizer is added during the preparation of the emulsion. I have found that generally from about .1 to 10 grams per mole of silver halide are quite adequate to accomplish the desired sensitization. Exposure of the treated emulsion in conventional photographic testing apparatus, such as an intensity scale sensitometer, will reveal the most advantageous concentrations for the present ketonic sensitizers in that particular emulsion. Such techniques are well understood by those skilled in the art.

The sensitizer addenda of the invention can be added to photographic emulsions using any of the well-known techniques in emulsion making. For example, the subject sensitizers can be dissolved in a suitable solvent and added to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar'to the technique used to incorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al. US. Patent 2,322,027, issued June 15, 1943, and Fierke et al. US. Patent 2,801,171 issued July 30, 1957. The solvent should be selected so that it has no harmful effect upon the emulsion in accordance with usual practice, and generally solvents or diluents which are miscible with water are to be preferred. Water alone is a dispersing medium for some of the sensitizers of the invention. In other cases, the subject sensitizers can be dissolved in solvents, such as ethanol, acetone, pyridine, N,N-dimethylformamide, etc., and added to the emulsion in this form.

The ketonic sensitizer addenda which have been described can be used in various kinds of photographic emulsions. In addition to being useful in orthochromatic, panchromatic, and infrared sensitive emulsions, they are also useful in X-ray and other nonoptically sensitized emulsions. They can be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts can be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. The subject addenda can be used in emulsions intended for color photography, for example, emulsions containing colorforming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsion of the mixed-packet type, such as described in Godowsky US. Patent 2,698,794, issued January 4, 1955, or emulsions of the mixed-grain type, such as described in Carroll and Hanson US. Patent 2,592,243, issued April 8, 1952. These ketonic sensitizers can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystals or in emulsions ployed for preparing silver halideemulsions, there can.

be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other collodial material such as colloidal albumin,'a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound, although gelatin is preferred. Some colloids which can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Patent [2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19-26% as described in U.S. Patent 2,327,808, of Lowe and. Clark, issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy US.

Patent 2,322,085, issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 025-15 on an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon US. Patent 2,541,- 474, issued February 13, 1951; zein as described in Lowe U.S. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol. polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US.

Patent 2,768,154, issued October 23, 1956; or containing cyano-acetyl groups such asthe vinyl alcohol-vinyl cyano acetate copolymer as described in Unruh, Smith and Priest US. Patent 2,808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a'vinyl group as described in Illingsworth, Dann and Gates US. Patent 2,852,382, issued September 19, 1958. If desired, compatible mixtures of two or more of these colloids can be employed for dispersing the silver halide in its preparation. of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethyleneterephthalate film and related films of resinous materials, as well as glass, paper,

metals and others.

The invention is further illustrated by the following examples ofpreferred embodiments thereof.

A high speed gelatino-silver halide emulsion panchrorm atically sensitized With a cyanine dye was prepared. The.

silver halide was composed of 6 molepercent of silver iodide and 94 mole percent of silver bromide. The emulsion comprised 245 g. of gelatin per mole of silver halide. Several typical ketonic sensitizers of the invention were incorporated in varying amounts in the prepared photographic emulsion. The emulsion containing the various sensitizers and control emulsions containing no sensitizer were coated on a cellulose acetate film support at a coverage of 430 mg. ofsilver per square foot. Samples The above-described emulsions The results of the sensitomctric tests are summarized by the data set out in the table below. The amount of addenda is set out as grams of addenda per mole of silver halide.

Table Amount Rela- Example Addenda oiAddentive Gamma Fog dag. Speed 1 Control 100 1.48 0.14 4,6-Diacetyl-3-hydroxy- 9.0 120 1.37 0.13

S-methylcyclohexanone.

2 Control 100 1.12 0.12 4,6-Diaeetyl-3-methyl- 0.3 112 1.10 0.13

2-cyclohexenone.

fi-A'cetyl-3rmethyl 2- 3.0 138 1.12 0.10

cyclohexeuone.

4. Control 100 1.20 0.13

- l-Carbethoxy-B-rnethyl- 0.9 115 1.22 0.13

Z-cyclohexenone. I

1 the speed of silver halide photographicemulsions without of ,the resulting photographic elements were exposed in.

the usual manner in an Eastman Type 1B Sensitometer,

then developed for five minutes at 68 F., and then fixed,

washed anddried in the usual manner. The developer had the following formula:

Potassium bromide Water to make one liter.

7 C I 11 03 Was:

1 Lacey disclosed in J. Chem. Soc., 1625 (1960). 45

undesirable increases in the .fog level.

The 4,6 diacetyl -'3 hydroxy-3-methylcyclohexanone sensitizer employed in Example 1 was prepared'by the procedure of Knoevnagel disclosed in Chem. Ber., 36, 2136 1903 r r The 4,6 diacetyl 3-methyl-2-cyclohexenone sensitizer employed in Example 2 was prepared by dehydrating the sensitizer utilized in Example 1. Thedehydration was effected by passing hydrogen chloride gas into 4,6-diacetyl- 3 -hydroxy-3-methylcyclohexanone in a;reaction vessel in an ice bath until turbidity was observed, and thereafter the reaction mixture was poured into a sodium carbonate. The prepared sensitizer melted at 75-76 C. and its carbon and hydrogen analysis calculated for Found: C=68.'1, 68.3; H=7.2, 7.4. 0:68.02; H=7.27.

The 6-acetyl-3-methyl-2-cyclohexenone sensitizer i employed in Example 3, was prepared by the procedure of This sensitizer boiled 7172 C./0.6 mm. and. had an index of refraction of 1.52 71. V 1

The 4-carbethoxy-3-methyl-2-cyclohexenone sensitizer Calculated:

employed in Example 4 was prepared by the pyrolytic distillation' of 4,6-dicarbethoxy -3-hydroxy-3-methycyclohexanone which was described by Rabe in Annalen, 332, 1 (1904). This'sensitizer was a pale yellow oil boiling 72 C./0.04 mm., having an index of refraction of n 1.4854 and a carbon and'hydrogen analysis calculated for C10H1403 of: I

Found: C=66.0; H=8.0. Calculated: 0:65.91; H=7 .75. j

The present inventionthus provides newand' useful photographic emulsions, and more particularly, photographicsilver halide emulsions sensitized with a novel class of sensitizers.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described in'the appended claims. a

I claim: e

1. A photographic silver halide emulsion containing a sensitizing amount of a cyclic sensitizing compound having a formula selected from the group-consisting of R1 R2 R R7 and R '=O EL- 0 0e wherein and R arealkyl radicals having 1m 6 car bon atoms, and R R R and R are selected from the group consisting of a hydrogen atom and a carbonyl radical having a formula selected from the group consisting of l u (|]R3 and OOR4 wherein R and R are alkyl radicals having 1 to 6 carbon atoms, at least one of R and R and at least one of R and R being one of said carbonyl radicals.

2. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer having the formula wherein R is a lower alkyl radical having 1 to 6 carbon atoms and R and R are selected from the group consisting of a hydrogen atom and a carbonyl radical having a formula selected from the group consisting of wherein R and R are alkyl radicals having 1 to 6 carbon atoms, at least one of R and R being one of said carbonyl radicals.

3. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer having the formula wherein R is an alkyl radical having 1 to 6 carbon atoms and R and R are selected from the group consisting of a hydrogen atom and a carbonyl radical having a formula selected from the group consisting of l H )R and COR4 wherein R and R are alkyl radicals having 1 to 6 carbon atoms, at least one of R and R being one of said carbonyl radicals.

4. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer havingthe formula 0 Rl la wherein R is an alkyl radical having 1 to 6 carbon atoms.

5. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer having the formula wherein R is an alkyl radical having 1 to 6 carbon atoms. 6. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer having the formula wherein R is an alkyl radical having 1 to 6 carbon atoms. 7. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer having the formula References Cited in the file of this patent UNITED STATES PATENTS 2,373,659 Carroll et al. Apr. 17, 1945 2,887,479 Heseltine May 19, 1959 FOREIGN PATENTS 557,659 Belgium June 15, 1957 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING A SENSITIZING AMOUNT OF A CYCLIC SENSITIZING COMPOUND HAVING A FORMULA SELECTED FROM THE GROUP CONSISTING OF 